UZC - Updated Zwicky Catalog

The Zwicky Catalog of Galaxies, with a magnitude limit m_Zw <=15.5,
has been the basis for the Center for Astrophysics (CfA) redshift surveys. To
date, analyses of the Zwicky Catalog and redshift surveys based on it have
relied on heterogeneous sets of galaxy coordinates and redshifts. In this
Updated Zwicky Catalog (UZC), some of the inadequacies of previous catalogs
are corrected by providing (1) coordinates with ~<2 arcsecond errors for all
of the 19,369 catalog galaxies, (2) homogeneously estimated redshifts cz
(radial velocities) for the majority (98%) of the data taken at the CfA
(14,632 spectra), and (3) an estimate of the remaining "blunder" rate for both
the CfA redshifts and for those compiled from the literature. For the reanalyzed
CfA data a calibrated, uniformly determined error and an indication of the
presence of emission lines in each spectrum are included. Redshifts (radial
velocities) are provided for the 7257 galaxies in the CfA2 redshift survey that
were not previously published; for another 5625 CfA redshifts (radial
velocities), the remeasured or uniformly rereduced values are listed.
Among the new measurements, 1807 are members of UZC "multiplets" associated
with the original Zwicky catalog position in the coordinate range where the
catalog is 98% complete. These multiplets provide new candidates for
examination of tidal interaction among galaxies. All of the new redshifts
(radial velocities) correspond to UZC galaxies with properties recorded in the
CfA redshift compilation known as ZCAT. The redshift catalog included in the UZC
is ~96% complete to m_Zw <=15.5 and ~98% complete (12,925 galaxies out of
a total of 13,150) for the right ascension ranges 20 hr >= RA(1950) <= 4 hr
and 8 hr <= RA(1950) <= 17 hr and the declination range -2.5 degrees <=
Dec(1950) <= 50 degrees. This more complete region includes all of the CfA2
survey as analyzed to the date of the publication of the UZC (1999).

This database was created by the HEASARC in October 2000 based
on a machine-readable version obtained from the CDS (Catalog J/PASP/111/438).
It was slightly revised in February 2001 (the 'redshift' parameters were
renamed as 'radial velocity' parameters to conform with the usage in other
similar HEASARC extragalactic catalogs).

Type_Radial_Velocity
The type of radial velocity for each galaxy, where E means it is derived from
emission lines(s), A from absorption line(s), and B means from both emission
and absorption lines.

UZC_Class
The UZC class code for each galaxy, which is a number from 0 to 4
according to the quality of the match with Digital Sky Survey (DSS) galaxies:

0: A "hit", where the Guide Star Catalog (GSC) and Zwicky-Nilson Catalog
(ZNCAT: Tonry and Davis 1979, AJ, 84, 1511) objects are separated in
position by a positional difference {DELTA}{theta} <= 180 arcseconds,
are comparable in brightness as determined visually, and there is no
other object within the field that could be the Zwicky Catalog galaxy.
Note that the ZNCAT B-band (m_Zw) and the GSC V- or J-band magnitudes
can differ significantly, because the expected colors for these galaxies
are in the range ~0.3 - 1.0 mags.
1: A "hit" with positional difference {DELTA}{theta} <= 180 arcseconds,
again with a GSC brightness in the vicinity of the ZNCAT value. However,
the field is centered on a GSC "star" rather than on a "nonstar", but
there is only one possible Zwicky Catalog galaxy nearby, within the field.
Thus, index 1 merely indicates that the nearest GSC object to the
ZCAT coordinates is a star rather than the appropriate galaxy.
2: A near "hit" with positional difference {DELTA}{theta} <= 180 arcseconds.
However, there is confusion because there are at least two galaxies with
an estimated spread in magnitudes |{DELTA}m| within the expected range,
either of which could be a Zwicky Catalog galaxy.
3: A near "hit" with positional difference {DELTA}{theta} <= 180 arcseconds,
but with |{DELTA}m| outside the expected range, raising suspicions about
the match of the GSC object to the Zwicky Catalog galaxy.
4: No "hit" at all for positional difference {DELTA}{theta} <= 180 arcseconds;
i.e., there is no match for a Zwicky Catalog galaxy.

Number_Neighbors
The number of UZC neighboring galaxies to this galaxy,
within 3 arcminutes.

ZNCAT_Name
The ZNCAT or Zwicky label, based on the 1950 equatorial
position; multiplets generally share a single such label.

Code_Radial_Velocity
A reference code indicating the origin of the radial velocity measurement,
for data taken at the CfA: Z for Z-machine, M for the MMT, and F for FAST
spectra taken from the authors' own and other projects. The label X flags a
low-S/N spectrum for Z-machine (FAST) measurements and indicates a low S/N
match with a spectrum at a radial velocity < 100 km/s, an indication that no
radial velocity could be determined.